Electrophoresis is an analysis method commonly used that involves migration of charged molecules and particles in a separation medium, usually a gel, when subjected to electrical field between two electrodes. Separation of molecules and particles such as proteins may be by isoelectric point (pI), molecular weight, electric charge, or a combination of these factors. The separation medium is usually placed on a support and two opposing ends of the medium are contacted with an electrode buffer in solution or rigid thrift. The electrodes may be inserted in vessels containing the electrode buffers. The buffer solutions from both the electrolytic medium and a reservoir for ions to keep the pH and other parameters constant. After separation, the molecules are detected and identified in different ways: e.g. visually by staining the gel or by optical means such as scanning or imaging the stained gel or labeller samples by a laser scanner or the like.
Electrophoresis process using gel is commonly used for separating biomolecules such as proteins, peptides, nucleic acids etc. Samples are handled in different types of screening, identifying (cell signaling, expression & purification) or in clinical tests. Protein samples can derivate from e.g. human, mammalian tissue, cell lysates or bacterial, insect or yeast cellular systems. The electrophoretic conditions for different types of molecules are different and have to be adapted in many cases. Thus, both the gel and the buffer solutions must often be chosen for each type of sample.
The preparation of the electrophoresis process includes several rather laborious steps. A suitable gel is chosen and placed or molded on a support. The gel is contacted with the buffer solutions. A common way is to have a gel slab in a cassette of glass or plastic in contact with the buffer solutions in buffer tanks. For each run the gel has to be placed on the support or the cassette to be prepared. Then the buffer tanks are filled with buffer solutions and the samples are applied on the gel. To go away from the handling of buffer solutions in buffer tanks it has been suggested, in WO 87/04948, to incorporate the buffer substance in a gel material whereby the buffer is obtained in the form of a buffer strip. In addition U.S. Pat. No. 6,368,481 discloses a precast electrophoresis cassette wherein buffer strips are incorporated as an integral part of the cassette.
Following the electrophoretic separation and in order to detect specific proteins in a given sample, the proteins may be transferred to a membrane (typically nitrocellulose or PVDF), where they are probed (detected) using antibodies specific to the target protein, a process commonly referred to as western blotting or immunoblotting. The primary method for transferring the proteins to the membrane is referred to as electroblotting and uses an electric current to pull proteins from the gel into the membrane. The proteins move from within the gel onto the membrane while maintaining the organization they had within the gel, whereby the proteins are exposed on a thin surface layer for detection. The proteins bind to the surface of the membrane due to its non-specific protein binding properties (i.e. binds all proteins equally well). In order to avoid unspecific binding of probing antibodies, remaining binding sites on the membrane may be blocked. During the probing (detection) process the membrane with the transferred proteins is incubated with specific primary antibody directed towards the protein of interest and secondary antibody e.g. for the protein of interest with a modified antibody which is linked to a reporter enzyme; when exposed to an appropriate substrate this enzyme drives a colorimetric reaction and produces a colour or by fluorescently labeled targets (dyes), that may be detected by a suitable imaging technique after drying.
All the steps involved in electrophoretic separation, probing and drying of the membrane containing the proteins are performed manually and also in different equipments. As different equipments are being used a technician needs to manually transfer the transfer sandwich or membrane from one equipment to another. So the likelihood of the membrane getting damaged is more. Now for drying the membrane, this needs to be done by placing the membrane in a location and air is supplied using a fan. Manual handling during the drying process also causes damage to the membrane as well as delay to whole analysis process. Moreover any damage to the membrane may result in inaccurate analysis of detection of different proteins.
Therefore there is a need for an improved system for performing electro-blotting electrophoretic separation, probing and drying of the membrane prior to detection of proteins in the membrane.